Spartan forces

Homer described the use of poison-tipped arrows during the Trojan War around 1200 bc and the Byzantines used Greek fire, a napalmlike mixture, against enemy navies. In 420 BC, during the Pelopormesian War, the Spartan forces used irritative fumes created by burning sulphur and tars to overrun an Athenian base, and Hannibal used beUadorma plants to induce disorientation in enemy troops during the Punic Wars (around 184 bc). 

B.C. Spartans forces use an early form of chemical warfare (CW) by burning wood soaked with pitch and sulfur at the siege of Plataea, thereby choking defenders. 

The following are programs created specifically for force field based simulations. There are also molecular mechanics programs bundled with the Spartan, Gaussian, and Hyperchem products discussed previously in this appendix. 

Molecular mechanics models differ both in the number and specific nature of the terms which they incorporate, as well as in the details of their parameterization. Taken together, functional form and parameterization, constitute what is termed a force field. Very simple force fields such as SYBYL, developed by Tripos, Inc., may easily be extended to diverse systems but would not be expected to yield quantitatively accurate results. On the other hand, a more complex force field such as MMFF94 (or more simply MMFF), developed at Merck Pharmaceuticals, while limited in scope to common organic systems and biopolymers, is better able to provide quantitative accounts of molecular geometry and conformation. Both SYBYL and MMFF are incorporated into Spartan. 

Any method that can calculate the energy of a molecular geometry can in principle calculate vibrational frequencies, since these can be obtained from the second derivatives of energy with respect to molecular geometry (Section 2.5), and the masses of the vibrating atoms. Some commercially available molecular mechanics programs, for example the Merck Molecular Force Field as implemented in SPARTAN [15], can calculate frequencies. Frequencies are useful (Section 2.5)... 

There are many different pieces of code available for molecular mechanics, ranging from the simple, such as MM2, to the elaborate, such as Cerius S YBYL, Spartan, and HyperChem. The code chosen for a particular model of catalytic processes depends on two factors (1) the complexity of the system that is to be studied, and (2) the amount of computer expertise available. Complicated structures, such as surfaces and zeolites, generally require specialized software packages for their visualization typically workers use commercial code with perhaps minor modifications. Simpler systems, such as modeling vanadium oxo species, are amenable to study using simpler codes, such as MM2, that are customized to suit the specific needs of the research group. It should be noted that the various available packages employ different force assumptions and some force fields are more suitable to one kind of application than to another (see Chapter 2). 

References to large-scale surfactant-enhanced aquifer remediation can be found in the literature [75, 76]. Childs et al. also report results from the test site at Dover Air Force Base, Delaware [76]. Large data sets are also available from field tests at Hill Air Force Base, Utah [47, 77, 78]. Other field tests were performed at the Canadian Forces Base, Borden [51, 53], Ontario, the Bachman Road site at Oscoda [79, 80], Michigan, as well as Camp Lejeune, North Carolina [81], Traverse City Coast Guard Base, Michigan [54], Spartan Chemical Company Superfund Site, Michigan [82] and the former Naval Air Station Alameda, California [82, 83]. In the latter case a 97% extraction of DNAPL is reported [83]. 

We first consider two model polypeptides an a-helix consisting of 15 alanine residues and an anti-parallel -sheet consisting of 17 glycine residues. Geometries of the polypeptides were obtained with the MMFF force field using the spartan... 

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